The present invention relates to a polarized light measuring apparatus and a phase plate measuring apparatus, both using Young's interferometer.
There exist conventional polarized light measuring apparatuses in which the polarization state of light is detected by measuring intensity of the light after passing through a single rotatable polarizer.
In another type of apparatus using a high speed light detector such as a streak camera, a rotatable polarizer is also provided removably in front of the high speed light detector. In this type of apparatus, a temporal waveform of light is first measured without using the polarizer, and again measured with the polarizer attached, and the difference between the two waveforms provides information on the polarization state of the light under measurement.
However, those prior apparatuses are disadvantageous in that the polarizer must be movable and actually be moved, and that sufficient information cannot be obtained in the case of circular polarization light and elliptical polarization light. More specifically, the circular polarization cannot be discriminated from the random polarization, and no information can be obtained on the rotational direction of the circular polarization light.
Further, there is known a phase plate measuring apparatus according to Senarmont's method. In this apparatus, incident light having horizontal linear polarization is passed through a sample, a quarter-wave plate and finally a polarizer, and output light is observed. Measurements are based on a rotation angle of the polarizer.
This type of apparatus also suffers from the problem of a necessity of moving the polarizer.